I usually have no trouble flagging a cab on Melgar, but occasionally they are more scarce for some reason or another. When that happens you can get the management wherever you are to call for one, but if you do that be sure to get the cab number and don't get into another one if it shows up before the one you called does. If people do that a lot at a particular location, the cab company may start refusing to send cabs there. That was the situation at Blue Angel when I was there last April.